A satellite positioning and navigation system mainly comprises GPS, Beidou, GLONASS, Galileo and the like. With the rapid development of satellite positioning technologies, the demand of people for the rapid and high-precision position information is daily increased. At present, an application range of the high-precision real-time satellite positioning and navigation is wider and wider, and the positioning precision of a user receiver is required to reach a millimeter scale and even a centimeter scale.
A single-point satellite positioning receiver technology has already been very mature. It can be known from a known principle that the satellite positioning is realized by utilizing an observed quantity and a user clock difference such as a pseudo-range of a group of satellites, satellite ephemeris, satellite launching time and the like. At least four satellites must be measured to obtain a three-dimensional coordinate on the ground. In this positioning process, three parts of errors exist: a first part of errors is caused by a satellite clock error, an ephemeris error, an ionosphere error, a troposphere error and the like; a second part of errors is an error caused by propagation delay; and a third part of errors is an intrinsic error of various user receivers and caused such reasons as internal noise, channel delay, multi-path effect and the like. Due to the existence of the errors, the precision of the single-point satellite static positioning is difficult to be less than 10 m, so a high-precision positioning requirement cannot be met.
In order to acquire higher positioning precision, a differential satellite positioning technology is mainly adopted. The principle of the differential satellite positioning technology is as follows: a differential satellite of a known precise three-dimensional coordinate is first used to position a ground reference station and to obtain a pseudo-range correction, a position correction or a carrier phase correction, the correction is then transmitted to the user receiver (a mobile station) in real time by virtue of a data link to correct measurement data of the user receiver, and a majority of errors are eliminated, thereby improving the satellite positioning precision of the user receiver. The user receiver can be in a stationary state, and can also be in a moving state. An information mode transmitted by the reference station can classify the differential positioning into three types, i.e., position differential, pseudo-range differential and phase differential. The differential satellite positioning is to add a (differential) correction signal on the basis of normal satellite positioning, and the correction signal improves the satellite positioning precision. Working principles of the three types of differential modes are identical, and the three types of differential modes are different in specific contents of transmitted corrections and differential positioning precision. In order to further improve the performance and application convenience, a plurality of reference stations can be connected into a network through a data processing center, thereby forming a ground enhancement system for transmitting the correction to the user receiver. We find that a principle of the existing differential satellite positioning technology can remarkably improve the positioning precision only by transmitting the correction through the data link by means of the reference station. However, the cost for building and using the reference station, the data link and the user receiver is very high, and the operation is complex; and furthermore, the biggest problem in the application is that the effective action distance and range of the reference station correction data is limited. The defects prevent the wide-scale use and popularization of the high-precision real-time satellite positioning and navigation.